1. Field of the Invention
The present invention relates to a door lock controller.
2. Description of the Related Art
FIG. 2 is a block diagram showing a conventional structure of a door lock controller that the invention is applied to. The door lock controller comprises input switches (operational input reception section) 1 and 3 for reception of a vehicle door locking or unlocking command and an electronic control unit 7 for drive control of a door lock motor 5 according to the input contents that are input through the input switches 1 and 3.
The input switch 1 is a manual switch that is provided on inside of a door at a driver""s seat for reception of a locking or unlocking command at on-off switching by the driver. The input switch 3 is a key-interlocked switch for reception of the locking or unlocking command at on-off switching that is interlocked with a locking or unlocking key operation at a key cylinder.
Each of the input switches 1 and 3 is provided respectively with two output signal lines 1a and 1b, or 3a and 3b, that are connected to input circuits 11 and 13, or 15 and 17, of the later-described electronic control unit 7; when the locking or unlocking command is not received, both of the output signals that come through the output signal lines 1a and 1b as well as 3a and 3b are maintained to be OFF and, upon reception of the locking signal, the output signals from the output signal lines 1a and 3a are switched from OFF to ON for a predetermined duration of time while, upon reception of the unlocking signal, the output signals from the output signal lines 1b and 3b are switched from OFF to ON for a predetermined duration of time (see FIGS. 3(a) and 3(b)).
Both of the input switches 1 and 3 have a structure wherein an operating piece thereof 1c or 3c that is normally set at OFF position is switched to a-contact side or b-contact side for a predetermined duration of time upon reception of the locking or unlocking command, which causes the output signal lines la and 3a or 1b and 3b to be grounded for the predetermined duration of time and thus the output signals from the output lines 1a and 3a or 1b and 3b are caused to switch from OFF to ON for the predetermined duration of time.
The electronic control unit 7 comprises the input circuits 11, 13, 15 and 17 for reception of output signals from the input switches 1 and 3, a microcomputer 19 for driving the door lock motor 5 according to the output signals from the input switches 1 and 3 which are received through the input circuits 11, 13, 15 and 17, output circuits 21 and 23 for driving the door lock motor 5 according to the controls of the microcomputer 19, and a power supply circuit 25 for generation of electric power source for the microcomputer 19.
The input circuits 11, 13, 15 and 17 are respectively connected, at one end, to input ports Pa1 through Pa4 of the microcomputer 19 and, at the other end, after being branched into two, are connected to the positive side of a battery 27 and to corresponding output signal lines 1a and 1b as well as 3a and 3b of the input switches 1 and 3. Accordingly, when the operating pieces 1c and 3c of the switches 1 and 3 are in the OFF position, all the input levels at the input ports Pa1 through Pa4 of the microcomputer 19 are high; when the operating pieces 1c and 3c are connected to the a-contact side, the inputs at the input ports Pa1 and Pa3 shift from a high level to a low level, and, when the operating pieces 1c and 3c are connected to the b-contact side, the inputs at the input ports Pa2 and Pa4 shift from the high level to the low level.
This causes the microcomputer 19 to recognize the switching from OFF to ON at the output signal from the input switch 1, which corresponds to locking or unlocking, through detection of shifts in the inputs from the high level to the low level at input ports Pa1 and Pa2, and to recognize the switching from OFF to ON at the output signal from the input switch 3, which corresponds to locking or unlocking, through detection of shifts in the inputs from the high level to the low level at input ports Pa3 and Pa4.
The output circuits 21 and 23 comprises: relays 21a and 23a for switching the connection of positive and negative power supply lines 5a and 5b for the door lock motor 5 either to the battery 27 side or to the ground side, and transistors 21b and 23b for driving the relays 21a and 23a in response to the shifts in the level of the outputs from the output ports Pb1 and Pb2 of the microcomputer 19 between the high level and the low level.
When the outputs from the output ports Pb1 and Pb2 of the microcomputer 19 are at the low level, the transistors 21b and 23b are turned off, and the relays 21a and 23a connect the power supply lines 5a and 5b for the door lock motor 5 to the ground. When the outputs from the output ports Pb1 and Pb2 of the microcomputer 19 shift to the high level, the transistors 21b and 23b are turned on and, the circuits being electrified with continuity from a positive terminal of the battery 27 to the ground via the relay coils 31 of the relays 21a and 23a and via transistors 21b and 23b, the relay coils 31 being excited, the operating pieces 33 of the relays 21a and 23a switching from the ground-side contact to the battery-side contact, the relays 21a and 23a connect the power supply lines 5a and 5b for the door lock motor 5 to the positive terminal side of the battery 27. The operating pieces 33 of the relays 21a and 23a are switched to the ground-side upon de-excitation of the relay coils 31 when the transistors 21b and 23b are turned off.
In a normal operating state, the microcomputer 19 controls the drive of the door lock motor 5 via the output circuits 21 and 23 through switching of the output state at the output ports Pb1 and Pb2, according to the contents of input from the input ports Pa1 through Pa4.
That is, the microcomputer 19 maintains the outputs at both of the output ports Pb1 and Pb2 to be low in a case of receiving neither locking commands nor unlocking commands from the input switches 1 and 3 while the output signals that are received from the input switches 1 and 3 through the input circuits 11, 13, 15 and 17 and the input ports Pa1 through Pa3 are OFF, wherein both the power supply lines 5a and 5b for the door lock motor 5 are connected to the ground by the relays 21a and 23a. 
When the output signals that are received from the input switches 1 and 3 through the input ports Pa1 and Pa3 are switched from OFF to ON for the predetermined duration of time upon reception of the locking commands from the input switches 1 and 3 as shown by A1 and A2 in FIGS. 3(a) and 3(b), the detection of switching from OFF to ON causes the microcomputer 19 to recognize the reception of the locking command and accordingly the door is locked by switching of the output level at the output port Pb1 from the low level to the high level for the predetermined duration of time as shown by B1 and B2 in FIG. 3(c) while the output at the output port Pb2 is maintained at the low level. In a case wherein the output from the output port Pb1 is switched to the high level at this time, since the power supply line 5a is connected to the positive terminal side of the battery 27 by the relay 21a , the electric current from the battery 27 flows from the power supply line 5a side to the motor 5 and forward drive (or reverse drive) of the motor for the predetermined duration of time effects locking of the door.
When the output signals that are received from the input switches 1 and 3 through the input ports Pa2 and Pa4 are switched from OFF to ON for the predetermined duration of time upon reception of the unlocking commands from the input switches 1 and 3 as shown by A1 and A2 in FIGS. 3(a) and 3(b), the detection of switching from OFF to ON causes the microcomputer 19 to recognize the reception of the unlocking command and accordingly the door is unlocked by switching of the output level at the output port Pb2 from the low level to the high level for the predetermined duration of time as shown by B1 and B2 in FIG. 3(c) while the output at the output port Pb1 is maintained at the low level. In a case wherein the output from the output port Pb2 is switched to the high level at this time, since the power supply line 5b is connected to the positive terminal side of the battery 27 by the relay 23a, the electric current from the battery 27 flows from the power supply line 5b side to the motor 5 and the reverse drive (or forward drive) of the motor for the predetermined duration of time effects unlocking of the door.
Incidentally, the microcomputer 19 is provided with a setting section 19a for presetting and registration of initial data in advance for initial setting at startup or reset (for example, a setup information recording section, such as a ROM) so that the microcomputer 19 can be initialized and set up according to the initial data at the setting section 19a in the case of startup and reset.
In the conventional door lock controller with the structure as described above, the microcomputer 19 is so set up as to reset on forcible assumption that the output signals from the input switches 1 and 3 are OFF signals that are input through the input ports Pa1 through Pa4.
Accordingly, in a case wherein the microcomputer 19 in the conventional door lock controller wherein the locking or unlocking command is input to the input switches 1 and 3 is reset due to such a mistake as caused by noise as shown by C1 in FIG. 4(a) during a period of time when the output signals from the input switches 1 and 3 are maintained to be ON as shown by A2 in FIG. 4(c), upon return to the normal operating state from the state wherein the reset is effected, as shown by D1 in FIG. 4(d), an erroneous recognition by the microcomputer 19 that the output signals from the input switches 1 and 3 have changed from OFF to ON, or an erroneous recognition that the locking command or the unlocking command has been received may result with erroneous output of the locking or unlocking command to the door lock motor 5, as shown by B3 in FIG. 4(e). Consequently, in spite the fact that the locking command or unlocking command has been received only once from the input switch 3, the door lock motor 5 carries out the locking or unlocking operation twice with the erroneous recognition that the command has been received twice and, since a user may recognize this as an erroneous operation, a problem is that the user is impressed with a sense of incongruity.
To describe the returning manner of the microcomputer 19 from the reset state more in detail, the microcomputer 19 is reset by noise or the like at time s0 and the reset is cancelled at time s1 and, when the microcomputer 19 starts initializing operation, the initializing operation forcibly sets the output signals that are input from the input switches 1 and 3 through the input ports Pa1 through Pa4 to be OFF by the initializing operation. Nextly, at time s2, upon completion of the initializing operation and return of the microcomputer 19 to the normal operating state, based on the contents of the initial setting, the microcomputer 19 forcibly assumes that the output signals that are input through the input ports Pa1 through Pa4 from the input switches 1 and 3 are OFF to return to the normal operating state. At time s3, when the microcomputer 19 detects actual output state (ON state) of the output signals that are input through the input ports Pa1 through Pa4 from the input switches 1 and 3, in spite that the output signals have been maintained at ON, output for locking or unlocking is carried out with erroneous recognition of switching from OFF to ON. For the period from time s0 to time s2, recognition contents of the output signals from the input switches 1 and 3 by the microcomputer 19 are undefined.
With consideration into the above-described problems, it is an object of the present invention to provide a door lock controller that enables prevention of erroneous double locking or unlocking operation by the door lock motor for each single input of locking or unlocking command in a case wherein the microcomputer is reset under influence of noise or the like.
In order to achieve the above object, according to the invention, there is provided a door lock controller comprising: an operational input reception section wherein, upon reception of a predetermined operational input to instruct locking or unlocking of a vehicle door, an output signal thereof is switched from OFF to ON for a predetermined duration of time; and a microcomputer that locks or unlocks the vehicle door by drive control of a door lock motor upon detection of switching of the output signal that is output from the operational input reception section from OFF to ON, wherein upon return from a reset state to a normal operating state, the microcomputer is set up in such manner as to return with a forcible assumption that the output signal that is input from the operational input reception section is ON.